RFR: 8359396: [Linux] Require Gtk3 >= 3.20 for glass-gtk

[Kevin Rushforth]

On Fri, 13 Jun 2025 01:00:31 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

> Upgrade the minimum required GTK version for JavaFX to GTK 3.20 to enable modern features and better Linux desktop integration.
> 
> JavaFX currently depends on GTK 3.8, [released](https://mail.gnome.org/archives/gtk-devel-list/2013-March/msg00108.html) in March 2013. This version is outdated and predates many useful GTK API improvements.
> 
> GTK 3.20 was [released](https://mail.gnome.org/archives/gtk-list/2016-March/msg00026.html) on March 21, 2016.
> 
> Updating the GTK minimum requirement to 3.20 would enable JavaFX to support new features, including the improvements proposed in  #1605 
> 
> Major Linux distributions already provide GTK 3.20 or newer:
> - Ubuntu LTS 18.04+ (ships GTK 3.22+)
> - Debian 9+ (ships GTK 3.22+)
> - Fedora 24+ (ships GTK 3.20+)
> - Oracle Linux and Red Hat Enterprise Linux 8+ (ships GTK 3.22+)

This seems like a very reasonable step. All currently supported Linux distros ship with a new enough version of GTK3 that they will be unaffected (and some out of support systems will continue to run).

I note that this will preclude running on Ubuntu 16.04 LTS, but given that even Ubuntu 18.04 LTS is out of support, I have no concern with this (other than a personal challenge: I have a dusty old desktop that is still running 16.04 ... time to upgrade or retire that system).

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PR Comment: https://git.openjdk.org/jfx/pull/1825#issuecomment-2970366831